The building in question is a single storey purpose built structure with 4 retail outlets.
Having read through the ANSI/BOMA Retail Buildings: Standard Methods of Measurement, it is not at all clear to me whether I should factor up a tenant area to take into account mechanical areas such as an electrical and sprinkler rooms that serve the whole building. Further, how would you suggest I deal with parking? The building is surrounded by a large parking area that served it and several other retail buildings just like it - in essence, an outdoor mall